BoilerFaultCodesYour boiler is currently firing up to provide central heating and is functioning as expected.
This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.
Technical description: Heat mode – burner on error
What causes this fault?
This is a normal status message indicating that your boiler is currently in 'Heating Mode' and the burner is successfully lit to provide warmth to your radiators. It appears when the internal thermostat calls for heat and the startup sequence has completed without any issues. Because this is a standard operating state rather than a failure, no repair is necessary.
This code is most frequently seen during the autumn and winter months when the central heating is programmed to be active for longer periods.
DIY fix possible
Check that your room thermostat is set to the desired temperatureEnsure your radiator valves are openMonitor the boiler to ensure it transitions to other codes once the heating demand is met
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like S.4 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Vaillant ecoTEC 65kW is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
Affiliate links — we may earn a commission at no extra cost to you.